Catheters for the introduction or removal of fluids may be located in various venous locations and cavities throughout the body of a patient. One important application of catheterization is for hemodialysis. Such catheterization may be performed by using a single catheter having multiple lumens, and a typical example of such a catheter is a dual lumen catheter in which one lumen introduces fluid and the other lumen removes fluid simultaneously therewith. An example of such a multiple catheter is the SPLIT CATH® catheter, sold by Medical Components, Inc. of Harleysville, Pa. Catheterization may also be performed by using a multiple lumen assembly consisting of separate, single lumen catheters inserted through one or two different incisions into an area to be catheterized, and an example of such a multiple lumen assembly is the TESIO® catheter, also sold by Medical Components, Inc.
Generally, to insert any catheter into a blood vessel, the vessel is identified by aspiration with a long hollow needle in accordance with the well known Seldinger technique. A thin guide wire is first introduced, typically through a syringe needle or other introducer device into the interior of a blood vessel. The needle or introducer device is then removed, leaving the distal end portion of the guide wire within the vessel and the proximal end portion projecting beyond the surface of the skin of the patient.
Several options are available to a physician for catheter placement. If the catheter to be inserted is significantly larger than the guide wire, an introducer sheath with a dilator device extending therethrough is passed over the guide wire to enlarge the vessel incision hole, or venotomy. After the venotomy is sufficiently enlarged, the dilator is removed, leaving the introducer sheath and guide wire in position inserted into the venotomy. The catheter is then inserted into the sheath, through the incision and into the blood vessel, and the sheath is then removed from around the exterior of the catheter by being split apart and peeled therefrom.
A tearaway introducer sheath that can be split away from the catheter as the sheath is being removed from the patient greatly facilitates the removal of the sheath. By splitting the sheath along its longitudinal axis as the sheath is being removed from the patient, the practitioner will be able to pull out the sheath in such a way that the portion removed from the patient is split, thereby not interfering with any hubs, luer fittings, clamps, cuffs or other accessories assembled to the catheter. For tearaway introducer sheaths having sheath tubes of polytetrafluoroethylene (PTFE), the polymeric material inherently contains longitudinally oriented molecules that easily split therealong with the hub component affixed to the sheath's tube. For tearaway sheaths of polyurethane, the sheath tubes are manufactured in a way that aids in the tearing of the sheath at two opposing angular locations on the circumference of the sheath, thereby splitting the sheath into two halves separated longitudinally through the center of the sheath; a conventional manner of manufacturing polyurethane sheaths is to provide a pair of opposed score lines along the sheath's tube.
An introducer sheath is generally constructed with a hub component affixed to the sheath's tube at its proximal end. The hub serves as a handle, and as a mating point for the insertion and locking of the dilator device. When a sheath needs to be split apart to be successfully withdrawn from the patient's body while leaving the catheter in place, the hub will also have to be split apart in order to clear the catheter. The hub generally is so made to have a pair of opposed laterally extending grippable wings or tabs for splitting, as well as longitudinally extending lines of weakness, such as opposed V-grooves or reveals, that are aligned with the score lines of the sheath tube, if any.
A dilator is often used to aid in the insertion of the sheath, and has a long tubular section, the outside diameter of which is slightly smaller than the inside diameter of the sheath. The dilator also has a pointed tip on its distal end and a hollow longitudinal passageway running the entire length thereof. The dilator is inserted into the patient's body through the sheath along the guide wire, allowing the distal tip to extend into the venotomy, carefully enlarging it. The dilator is then removed along the guide wire prior to insertion of the catheter along the guide wire and into the sheath.
However, after the dilator is removed, and before the catheter is inserted through the sheath, the sheath becomes an open conduit, allowing blood to spurt from the vessel through the sheath or allowing air to be aspirated into the vessel through the sheath, neither of which is desirable or permissible. The practitioner conventionally has had to place a thumb or finger over the proximal opening of the sheath to prevent blood loss and air embolism; however, this restricts the practitioner's hand movement, and is not a reliable method. Other sheath designs attempt to solve this problem by utilizing plugs or clamps. These designs require a modification of the standard catheterization technique and are usually cumbersome to use.
It is desirable to provide a tearaway sheath having an integrated valve such that after dilator removal, the valve prevents blood or air passing through and from the sheath, prior to insertion of the catheter.
It would also be desirable to provide an integrated valve that operates automatically to close and seal the opening as soon as the dilator is removed.
It would be further desirable to provide an integrated valve that provides an audible signal as it closes thereby notifying the practitioner that the valve is closed.